It is known to cover open top-end vehicle platforms, such as railway cars and tractor trailers, with a tarp whereby to protect merchandise during transport. It is also known to provide a slidable cover assembly for such platforms and such is exemplified by, for example, U.S. Pat. Nos. 5,152,575; 6,250,233 and European Patent EP 0 955 196 A1. Several other patent publications relate to covers for open top-end containers wherein the cover spans only the open top end of the transport container.
There are several problems with slidable cover assemblies and, for example, the lifespan of such assemblies is fairly short due to malfunctions and wear-and-tear. Some of these problems are attributed to the fact that these covers are damaged during installation and removal and by loading and unloading equipment working in the vicinity of these covers. For railway cars these covers are very large and difficult to install due to their large size and weight.
Further problems with slidable cover assemblies are that they are not able to slide in a way as to expose the entire area of the platform for loading and unloading merchandise and therefore need to be disassembled and this is a time-consuming and expensive job, often idling the railway car(s) for long periods of time. The structures supporting slidable cover assemblies have not been found adequate to provide proper operation and often leads to damage of the tarp during the displacement of its support frame assembly. Also, they do not provide adequate support of the top wall of the cover which may be subjected to snow or ice loads during winter months. Furthermore, the structure of these slidable cover assemblies has not been found adequate to protect the cover during displacement of the merchandise carrying vehicle platforms wherein air infiltrates behind the cover applying outward pressure thereto and causing ruptures in the tarp. Furthermore, with railway car platforms, the tarp is subjected to lateral pressure when two trains move in opposite directions in side-by-side relationship causing shearing forces on the side walls of the tarp. Many of these slidable cover assemblies are also motor-operated due to their heavy weight and this increases cost. Still further, the support mechanisms of these slidable covers often become defective and in order to effect repair, it is necessary to remove the entire slidable cover assembly from the transport vehicle platforms for maintenance purpose. If the vehicle platform is carrying merchandise this maintenance becomes very costly.